Mordekaiser vs Swain

Aim Obliterate (Q) at a lone enemy: if only one enemy is hit, the damage increases.

Hit champions or monsters three times, then stay close: Darkness Rise (passive) then surrounds you with a damage aura and gives you move speed.

Pull your targets into the Obliterate (Q) zone with Death's Grasp (E): each spell that hits also counts toward Darkness Rise (passive).

Cast Indestructible (W) when you're taking damage: it turns stored damage into a shield, and a recast converts part of it into health.

Cast Realm of Death (R) on their carry, or their jungler near an objective: you isolate them with you, steal part of their stats, and keep them if you kill them.

Get out of the Nevermove (E) path as it comes back: it only roots on its return to Swain, then he can pull each rooted champion to him.

Leave the area as soon as Vision of Empire (W) appears: it strikes and slows 1.5 seconds later, and each champion hit gives him a Soul Fragment.

During Demonic Ascension (R), back off and hit from range if you can: he only drains nearby enemies, and his form ends when he stops draining.

If you have Grievous Wounds, apply it during Demonic Ascension (R): the drain heals him every second, and that healing keeps him alive.